Open the info.plist in the shazam app and you will find the identifier there.

Edit: the icon name will be different also

THAT DID IT!! Thanks Mcooper, Fattone and Krima for helping me to get to the bottom of this. One of the dangers of the tweak called: IconRenamer is that you can think you have "Shazam" when you actually have "Shazam Encore".